<!DOCTYPE html>
<html>
<head>
	<meta charset="utf-8">
	<meta name="viewport" content="width=device-width, initial-scale=1">
	<title>CSS outline 制作边框</title>
</head>
<style type="text/css">
	*{
		margin: 0;
		padding: 0;
	}
	.wapper{
		width: 100px;
		height: 100px;
		background-color: red;
		margin: 100px auto;
		/*	外边框	*/
		outline: 1px dashed; blue;
		/*	内边框	*/
		outline-offset: -10px;
	}
</style>
<body>
	<div class="wapper">
		
	</div>
</body>
</html>